1. Field of the Invention
The present invention is related to a retaining tool with rotational locating device and particularly to a rotational locating device capable of fixing a heat sink to a central processing unit (CPU).
2. Brief Description of the Related Art
Due to electronic product such as computer being popularly used and being widely applied to any fields, the electronic technology industry develops rapidly toward high speed operation and high data storage capacity and it results in high heat during the electronic parts running under high speed.
Taking the host unit of a computer as an example, most heat therein is generated from the CPU and the heat staying in the CPU exceeding the allowable value leads to shut down of the computer. Further, in order to solve problem relating to electromagnetic wave radiation, the host unit is enclosed with a casing. Under this circumference, how to release the heat from the CPU and other heat generating components as fast as possible becomes an important subject has to be cared.
Usually, heat dissipation of the CPU is done with a heat sink with a plurality of cooling fins being disposed at a side thereof and another side thereof contacting the CPU. In this way, the heat generated by the CPU is able to transmit to the cooling fin end and the heat is capable of moving outward via radiation or a fan, which is added to the heat sink. Thus, it is necessary for the CPU keeping contact with heat sink tightly, otherwise, it is easy to become heat resistance increase and degrade effect of heat dissipation largely. The conventional fixing device for the CPU being joined to the heat sink shown in FIGS. 1 and 2 provides a locking part 1 and the locking part has a locking bar 11 with an end thereof extending downward a vertical part 110. The lower end of the vertical part 110 has a through hole 111 capable of engaging a jut (not shown) at a lateral side of a joining seat H bearing a CPU C. Another end of the locking bar 11 has slots 112 for being inserted with a hanging part 12. The hanging part 12 with a fitting hole 121 is pivotally jointed to a handle O with an eccentric hole O1 with a pivot S passing through the fitting hole 121 and the eccentric hole O1. When the handle O is turned with respect to the pivot S, the hanging part 12 moves vertically to secure a heat sink R to the CPU C via a through hole 122 engaging another jut H1 at the other side of the joining seat H.
However, the locking part 1 forcing the heat sink R to approach and contact the CPU C by means of an eccentric device or cam producing a restriction force has the following deficiencies:
1. The handle O has a low dead point such that it is not easy to press the locking part 1 firmly.
2. Due to insufficient binding force being created by the dead point, it is easy to result in lock failure or loosening in case of dropping down and occurring shock.
3. The handle O easily becomes tilt after the locking part 1 being in a state of engaging.
4. Undesirable contact is formed between the heat sink R and the CPU C to increase thermal resistance to decrease effect of heat removal.